To make a cake that looks like the earth, you can either make a flat circle and paint it to look like the earth, make a semi-sphere cake and likewise paint it with the appropriate land and water divisions, or go all out and make a spherical cake that will look exactly like a geographic globe. You can buy small ball-shaped cake pans for a small sphere, but these instructions are for a larger, five-layered cake that will most resemble an earth globe using polystyrene foam as the bottom support.
Butter and flour the inside of a three-quart metal bowl.
Bake a cake mix of your choice in the bowl. Bake at 121 degrees Celsius (250 degrees Fahrenheit) for about two hours to avoid scorching on the outside and underbaking on the inside. Allow to cool.
Make or purchase a filling of your choice. Allow to cool.
Cut a twelve-inch diameter polysterene ball in half using a serrated knife (preferably electric). Cut a small piece off the bottom of one half (you will not need the other half). This flattened edge will keep your globe cake from rolling. This is the base of your cake.
Push a 250 mm (10 inch) wooden dowel through the centre of the polystyrene half-sphere. It will stick up 100 mm (4 inches) above the polystyrene. This will help support the layered top of the cake, but will be up to 50 mm or 2 inches shy of the top.
Roll out a piece of fondant icing into a thin, 300 mm (12 inch) diameter circle. Place on top of polystyrene base to form a barrier between the base and the cake.
Slice the cooled cake into five layers (four cuts) with either a serrated knife or a long piece of dental floss held taught between both hands.
Place largest layer of cake onto polystyrene base. Spread with filling.
Repeat with remaining four layers.
Cover entire sphere with light blue fondant. To tint fondant, use paste food colouring and knead into fondant until uniformly coloured.
Add land shapes to earth cake by either tinting additional fondant green (or brown) and cutting into shapes and pressing onto blue sphere, or by painting land shapes directly onto blue sphere. Be sure to thin paste food colouring with alcohol (vodka or other tasteless alcohol) rather than water. Paint green (or brown) land shapes on blue fondant with paintbrush.